Hot electron transmission in metals using epitaxial NiSi2/n-Si(111) interfaces

We have investigated hot electron transmission across epitaxial metal-disilicide/n-Si(111) interfaces using ballistic electron emission microscopy (BEEM). Different crystal orientations of epitaxial NiSi2 were grown on a Si(111) substrate using molecular beam epitaxy. The presence of different interfaces of NiSi2 on Si(111) were confirmed by high resolution transmission electron microscopy. Electrical transport measurements reveal a clear rectifying Schottky interface with a barrier height of 0.69 eV. However, using BEEM, three different regions with different transmissions and Schottky barrier heights of 0.65 eV, 0.78 eV, and 0.71 eV are found. The addition of a thin Ni film on the NiSi2 layer strongly reduces the transmission in all the three regions and interestingly, almost equalizes the transmission across them.